Pneumatic hammer.



G. L. ROBERTSON.

PNEUMAIIG HAMMER. APPLIGATION FILED Amma, 1912.

Patented Dec. 24, 1912.

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; UNITED STATES PATENT FFICE.

GEORGE L. ROBERTSON, or PHILADELPHIA, PENNSYLVANIA, AssIGNoE or 'ONE-HALF TD JOSHUA R. RITCHIE, 0F PHILADELPHIA, PENNSYLVANIA.

To all whom -itimafy concern: v

Be it known that I, GEORGE L. ROBERTSON, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Pneumatic Hammers, of which the followin is a specification.

y invention relates to improvements in pneumatic hammers, the `object of the invention being to provide a pneumatic hammer which isso constructed that vibrations of the hammer are not transmitted to the op erator holding the hammer, but are absorbed within the hammer.

A further object is to provide a pneumatic hammer having a movable barrel cushioned by means of a. spring within a jacket and guiding the movement of a plunger so that the vibrations caused by the latter are imparted to the barrel, and are absorbed by the cushioning means therefor, and do not reach the operator holding the hammer.

With these and other objects in view, the invention consists in certain novel features of construct-ion and combinations and arrangements of parts as will be more fully hereinafter described and pointed out in the claims.

In the accompanying drawings: Figure l is a view in longitudinal section illustrating my improvements. Fig. 2 is a view in cross section on the line 2-2 of Fig. 1, and Fig. 3 is a view in cross-section on the line 3 3 of Fig. 1.

1 represents a metal jacket which is. cylindrical in form throughout the greater porn tion of its length, but at one end is tapered or made conical as shown at 2 and is provided with ascrew-threaded opening 3 in its end to receive the shank 5 of the set 6. The shank 5 is screwed tightly into the end of the jacket, and projects inwardly into the cylindrical bore 7 of my improved barrel 8. This barrel 8 Iits Within the jacket, but is free to slide longitudinally therein. The opposite end of the jacket is .enlarged in diameter as shown at 9, and is internally screw-threaded engaging external screwthreads on a cylindrical casing 10. This casing 10 is integral with a handle l11 havinga passage 12 therethrough forthe air, and a valve l-controlling the flow of air.

The passage 12 discharges into the end of casing 10 and in this casing a piston 14 is Specification o! Letters Patent.

Application led August 224, 1912. Serial No. 716,600.

Patented 1390.24., 1912'.

mounted to slide. This piston 14 is lixed'to the valve box 15 and the latter located at the end of barrel 8. The barrel 8 is provided with passages 16 for the air to compel the reciprocat-ion of the plunger 17 which snuglyfits within the bore of the barrel and strikes the shank 5 of set 6 when operated. The inner end of the barrel bore is closed by a perforated integral partition 8a which Acoinpels the barrel to move when thev plunger moves inwardly.

The valve box l5 is provided with a suitable valve (notshown) controlling the passage of air through the several ports therein and through-the passages 16, and this box is connected to the end of the barrel by means of dowels 18 to maintain the passages inv alinement. Ports 19 are provided in the jacket at the point where said jacket increases in diameter, so that the air is free to escape after passing through ports 20 in' the valve box. It is to be understood that l the piston 14 has a central passage 21, so that thev air from passage 12 is free to iow into the center of the valve b'ox, and I do not limit myself to any particular construcf' tion of valves, one arrangement of passa-ges controlling the operation of the plunger, as

my improvements are applicable with any i structures capable of performing this function. Between the piston 14 andthe end of casing 10, a. coiledspring 22 is located and exerts pressure on the piston tending always to project the barrel 8 against the conical end of jacket l.

In operation,the set 6 is positioned against the rivet .and while tightly pressed thereagainst, the valve 18 is operated to admit the air and the plunger 17 reciprocates inthe barrel and str'kes the shank 5 of the set. The vibration Izaused by this impact and by the movement lof the plunger causes the barrel 18 to move longitudinally within the jacket, and this movement is absorbed by the spring 22 preventing transmission of such vibration to the jacket and to the handle. The spring therefore acts as a shock absorber and the tension of this spring may described without departing from my in be adjusted by screwing the jacket onto the cli 'lot limit myself to orth. but consider .c such changes and sl within thc spirit j nded clainis..

l my invention, what ot the Having thus l cl: n new and t csiro to secure by Leb ter; A atent is: v

l.. E. pnenma hammer comprising a jacket, a reciprocating plunger in the acket, means within the. jacket controlling the movement et the plunger, and shock absorbmeans within the jacket absorbing the itions caused by the plunger, substantially as described.

r i pneumatic hammer comprising a a tool located in one end ot' the plunger in the barrel, and elastiomcans cnshio ing the movement of the barrel, substantialb as described.

3. A 1incumatic hammer comprising a jacket, a tool located in one end ot the jacket having a shank projecting into the jacket, a barrel mounted to move longitudi- .nally in the jacket and having a central bore achet, a tool located in one end of the jacket, a barrel mounted to move longitudinally in the jacket and having a central.

bore receiving the shank of the tool, a plunger mounted to reciprocate inA the-barrel, a spring exerting .pressure against one end ot the barrel, a valve. box located at one end of the barrel, ay piston on said valve box, and

la springA bearing against said piston, substantially as described.

(in. pneumatic hammer comprising a jacket, a'tool fixed .in one end of the jacket,

the other end ot said jacket lenlarged trans- `et a barrel movable in the jacket, a'

the movement of the barrel, a valve box j y jacket having a shank 'projecting into the,

p incense and cushioning means between the piston and the end of the cylinder, substantially as described.

A. pneumatic hammer'comprising a jacket, a tool fixed in one endof the jacket, the other end of said jacket enlarged transversely 'and internally screw-threaded, w ahandle having an integral cylindrical eX- ternally screw-threaded casing screwed into the enlarged end of the jacketya barrel in the jacket, a plunger mounted to move n the barrel, a valve boX against one end of the barrel, apiston against the valve boX, said piston tltting snugly Within the casing and having a central opening, said handle having an air passage communicating'with the end of the casing, and a coiled spring in the casing between the end of the casing and the piston, substantially as described.

8. A pneumatic hammer comprisingA a jacket having a reduced conical end and having an enlarged end, both ends internally screw-threaded, a tool havinga shank screwed into the conical end of the acket, a barrel fitting the smaller diameter of the jacket' andV having a central longitudinal bore receiving the end of the shank, a plnn ger mounted to reciprocate in the bore of the barrel, a valve box located against the end of the barrel, a piston xed to the valve box and having a central opening therein, a cylindrical casing externally screw-threaded and screwed into the larger end of the jacket and receiving the piston therein, a jam nut on said casing against the end of the jacket,'a coiled spring in the casing bearing aga-instthe piston, and means for directing air into the end 'of the casing, substantially as described.

ln testimony whereof I have signed my name to this specication in the presence of two subscribing witnesses.

GEORGE L. ROBERTSN.'

Vlitnesses:

S. W'. FOSTER, CHAs. E. Porre. 

